JPH05246337A - Power steering device - Google Patents

Abstract

PURPOSE:To provide a power steering device of which the operating quantity of the handle correctly corresponds to the steering angle of wheels even if oil leakage is generated. CONSTITUTION:This power steering device is provided with a hydraulic type orbit roll (registered trademark) having a rotary changeover valve part 9, a first gear 33 provided on one end of a sleeve 15 which is internally mounted in the changeover valve part 9 and rotated in a decided direction so as to close the changeover valve part 9, a second gear 34 engaged with the first gear 33, a rotary shaft connected to the second gear 34 at its one end, and a link mechanism to rotationally move the other end of the rotary shaft 35 according to the steering angle of wheels. By mechanical feedback of actual steering angle of the wheels through the link mechanism, the rotary shaft 35, and the gears 33, 34, the sleeve 15 can be rotated in the decided direction, and hence pressure oil is continuously supplied to a cylinder up to closing of the changeover valve part 9 with the sleeve 15 even if oil leakage is generated, so that the operating quantity of the handle correctly corresponds to the steering angle of the wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device having an all-hydraulic orbit roll provided in an industrial vehicle such as a wheel loader.

[0002]

2. Description of the Related Art Conventionally, as a power steering device of this type, there is one shown in FIGS. 7 and 8, for example. That is, FIG. 7 shows a hydraulic circuit. When the handle 70 is in the straight-ahead position, the spool 73 of the switching valve portion 72 in the orbit roll 71 is in the C position, and the pressure oil is not supplied to the steering cylinders 74 and 75.

When the handle 70 is rotated counterclockwise from the straight-ahead position, the spool 73 is switched to the C to L positions, and the pressure oil from the hydraulic pump 76 is adjusted to the steering priority flow control valve 77.
Pass into Orbit Roll 71. Further, the pressure oil passes through the metering section 78 and the spool 73, and the first
It flows into the tail side of the cylinder 74 and the rod side of the second cylinder 75. At the same time, the pressure oil on the rod side of the first cylinder 74 and on the tail side of the second cylinder 75 flows into the recovery tank 79 through the spool 73. Then, the cylinder 74,
When a predetermined amount of pressure oil is supplied to 75 and the wheels switch by a predetermined angle, the spool 73 switches to the L to C positions and the cylinder
The supply of pressure oil to 74 and 75 is stopped.

When the handle 70 is rotated clockwise, the spool 73 is switched to the C to R positions, the pressure oil flows into the tail side of the second cylinder 75 and the rod side of the first cylinder 74, and The pressure oil on the rod side of the two cylinders 75 and on the tail side of the first cylinder 74 is collected in the collection tank 79.

The operation of the orbit roll 71 will be described with reference to FIG. 8. When the handle 70 is rotated to the left, the spool 73 rotates via the steering shaft 82.
The spool 73 is displaced relative to the sleeve 83.
As a result, the oil passage is opened, and the pressure oil (dotted arrow A) flowing from the P port 84 passes through the oil hole of the sleeve 83, the oil groove of the spool 73, and the oil hole of the sleeve 83 of the housing 85. It is sent from the oil passage to the metering unit 78 to rotate the rotor 86. The pressure oil discharged by the rotation of the rotor 86 (the one-dot chain line arrow B) is sent to the switching valve unit 72, and the sleeve.
It flows into the tail side of the first cylinder 74 and the rod side of the second cylinder 75 from the L port 87 via 83 and the spool 73. At the same time, the pressure oil (two-dot chain line arrow C) on the rod side of the first cylinder 74 and the tail side of the second cylinder 75 is discharged and returned to the R port 88, and the sleeve 83 and the spool 73.
Through T port 89.

When the rotor 86 rotates as described above, the drive shaft 90 and the sleeve 83 rotate together. That is, when the handle 70 is turned to rotate the spool 73, the sleeve 83 follows the spool 73 by the same amount and the displacement of the spool 73 is eliminated.
72 oilways are fully closed. As a result, the rotor 86 rotates by the rotation angle of the handle 70, and the pressure oil displaced by the rotor 86 is sent to the cylinders 74 and 75.

When the handle 70 is rotated to the right, the rotor 86 rotates in the reverse direction, and the suction and discharge of the rotor 86 are reversed. As a result, pressure oil flows from the R port 88 to the cylinder 74,
The pressure oil flowing to 75 and discharged from the cylinders 74 and 75 returns to the L port 87.

The handle 70 is provided with a knob 91 for facilitating the rotating operation.

[0009]

However, according to the above-mentioned conventional type, due to the oil leakage in the switching valve portion 72 of the orbit roll 71, the metering portion 78 and the cylinders 74 and 75, the rotation operation amount of the handle 70 and The turning angles of the wheels do not correspond exactly. Then, for example, when the handle 70 is rotated counterclockwise from the straight traveling position and then rotated right to return to the straight traveling position, the rotation speed of the handle 70 when rotating left and the return rotation (in this case, right rotating) Different from the rotation speed. As a result, there is a difference between the amount of oil leakage during left rotation and the amount of oil leakage during return rotation (right rotation).
After rotating the handle 70, the position of the knob 91 was displaced each time the handle 70 was returned to the straight traveling position. As a result, during straight running, the knob 91 may be in front of or on the other side of the driver, which may lead to an erroneous operation of the steering wheel 70.

The present invention solves the above problems, and an object of the present invention is to provide a power steering apparatus in which the operation amount of the steering wheel and the turning angle of the wheels correspond accurately even if oil leaks. ..

[0011]

In order to solve the above problems, a power steering device according to the present invention is a power steering device provided in an industrial vehicle, and is a hydraulic orbit roll using a rotary switching valve. A steering cylinder for switching the turning angle of the wheels is connected to the downstream side of the switching valve, and the first gear is provided at one end of a sleeve which is built in the switching valve and rotates in a predetermined direction to close the switching valve. A second gear that meshes with the first gear is provided, a rotary shaft is connected to the second gear, and a link mechanism that rotates the rotary shaft according to the turning angle of the wheel is provided.

[0012]

With the above structure, when the handle is rotated, the switching valve of the orbit roll is opened and the pressure oil is supplied to the steering cylinder, so that the wheels are switched to the left and right. Then, as the wheels are switched, the rotating shaft rotates in conjunction with the link mechanism. The rotational force of the rotating shaft is transmitted from the second gear to the sleeve in the switching valve via the first gear, so that the sleeve rotates in a predetermined direction and closes the switching valve. As a result, the supply of pressure oil to the steering cylinder is stopped, and the wheels are stopped in a switched state. In this way, the actual turning angle of the wheels is mechanically fed back by the link mechanism, the rotating shaft, and the gears to rotate the sleeve in a predetermined direction, so that even if oil leaks, pressure is applied until the sleeve closes the switching valve. Since the oil is continuously supplied to the steering cylinder, the amount of steering operation of the steering wheel and the turning angle of the wheels correspond exactly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 6 shows a hydraulic circuit of the power steering device, in which a steering priority flow rate adjusting valve 2, a hydraulic orbit roll 3, a first steering cylinder 4 are sequentially provided downstream of a hydraulic pump 1 which supplies pressure oil to the steering cylinder. The second steering cylinder 5 and the recovery tank 6 are connected.

As shown in FIGS. 1 and 2, the orbit roll 3 has a steering wheel 7 and a steering wheel 8.
Is linked to. That is, the orbit roll 3 is composed of a rotary type switching valve portion 9 and a metering portion 10. A sleeve 15 rotatable about a longitudinal axis 14 is provided in the housing 11 of the switching valve unit 9, and a cylindrical spool rotatable relative to the sleeve 15 is provided in the sleeve 15. 16 is inset. These sleeves
A plurality of oil grooves 17 and 18 for guiding oil and a plurality of oil holes 19 and 20 are formed on the outer peripheral surfaces of 15 and the spool 16. The upper end of the spool 16 penetrates above the housing 11 and is connected to the lower end of the steering shaft 7. Further, a plurality of oil grooves 21 are formed on the inner peripheral surface of the housing 11.

On the outer peripheral surface of the housing 11, a P port 22 connected to the hydraulic pump 1 side, L and R ports 23 and 24 connected to the first and second steering cylinders 4 and 5,
A T port 25 connected to the recovery tank 6 side is formed. An end cap 26 is attached to the bottom of the housing 11.

A connecting pin 27, which is orthogonal to the longitudinal axis 14 of the sleeve 15, is fitted in the sleeve 15, and the connecting pin 27
One end of a drive shaft 28 rotatably provided in the spool 16 is connected to the 27. The other end of the drive shaft 28 is supported by a bearing 31 provided in the end cap 26 and penetrates below the end cap 26. A ring-shaped oil groove 32 is formed in the end cap 26 so as to surround the drive shaft 28, and the oil groove 32 communicates with the inner peripheral surface of the housing 11 via an oil passage 30.

Metering section of the orbit roll 3
Reference numeral 10 denotes a small-diameter first bevel gear 33 (an example of a first gear) provided on the other end of the drive shaft 28, and a large-diameter second bevel gear 34 (of the second gear) which meshes with the first bevel gear 33. One example) and a rotary shaft 35 whose one end is connected to the second bevel gear 34. These first and second
The bevel gears 33 and 34 are provided in the gear box 36, and the gear box 36 is attached to the lower portion of the end cap 26. The rotary shaft 35 is supported by a bearing 37 provided on the gear box 36 side and is rotatable about a horizontal axis 38. As a result, when the rotating shaft 35 rotates, this rotational force is transmitted to the drive shaft 28 via the second bevel gear 34 and the first bevel gear 33, and the sleeve 15 rotates via the connecting pin 27. Incidentally, 39 is an oil seal.

As shown in FIGS. 3 to 5, reference numeral 41 denotes a vehicle body of a wheel loader which is an example of an industrial vehicle.
41 comprises a front frame 43 having a front wheel 42 and a rear frame 45 having a rear wheel 44. The rear end of the front frame 43 and the front end of the rear frame 45 are connected via a connecting shaft 46, whereby the front frame 43 is connected to the rear frame.
It is rotatable in the left-right direction about the vertical axis 47 with respect to 45. The connecting shaft 46 is erected on the rear frame 45 side, and the rear end of the front frame 43 is fitted into the connecting shaft 46 from above.

The rear frame 45 is provided with a bracket 48 protruding above the front frame 43.
A mounting shaft 49 is erected on the upper surface of the. The axis of the mounting shaft 49 coincides with the vertical axis 47 of the connecting shaft 46, and the swing plate 50 is fitted into the mounting shaft 49. As a result, the rocking plate 50 is rotatable in the left-right direction about the vertical axis 47. Then, one end of the swing plate 50 is connected to the front frame 43 via the pin 53.
It is connected to the side. A first arm 54 is erected on the other end of the swing plate 50.

A second arm 55 is attached to the other end of the rotary shaft 35. The first arm 54 and the second
The arm 55 is connected by a connecting arm 58 via ball joints 56, 57. Here, the swing plate 5
The 0, the first arm 54, the second arm 55, and the connecting arm 58 are examples of the link mechanism 64.

The first and second steering cylinders 4,
Reference numerals 5 are provided on both sides of the rear frame 45, and the steering wheel 8 and the orbit roll 3 are installed in a driver's seat provided on the rear frame 45. Also, handle 8
A knob 59 for facilitating the rotating operation is provided on the.

The operation of the above structure will be described below.
As shown in the hydraulic circuit of FIG. 6, when the handle 8 is in the straight traveling position, the spool 16 of the switching valve portion 9 in the orbit roll 3 is in the C position, and the pressure oil is not supplied to the steering cylinders 4 and 5. As a result, the front wheels 42 are maintained in the straight traveling direction.

When the handle 59 is rotated counterclockwise from the straight position by turning the knob 59, the spool 16 is switched to the C to L positions, and the pressure oil from the hydraulic pump 1 passes through the steering priority flow rate adjusting valve 2 and the orbit roll. Switching valve section 3
Flow into. Further, the pressure oil is supplied to the tail side of the first cylinder 4 and the rod side of the second cylinder 5 through the switching valve section 9. At the same time, the pressure oil on the rod side of the first cylinder 4 and on the tail side of the second cylinder 5 flows into the recovery tank 6 through the spool 16.

The operation up to this point will be described with reference to FIG.
When the steering wheel 8 is rotated counterclockwise by turning 59, the spool 16 rotates in one direction via the steering shaft 7, so that the spool 16 is displaced relative to the sleeve 15. As a result, the oil passage is opened, and the pressure oil (dotted arrow A) flowing in from the P port 22 is switched to the sleeve 15.
Oil hole 19, oil groove 18 on spool 16, and oil hole on sleeve 15
End cap from oil passage 30 of housing 11 through 19
26 through the oil groove 32, and again through the sleeve 15 and the spool 16 from the L port 23 to the tail side of the first cylinder 4 and the second side.
It flows into the rod side of the cylinder 5. At the same time, the pressure oil on the rod side of the first cylinder 4 and the tail side of the second cylinder 5 (dashed line arrow B) is discharged and returned to the R port 23, and then flows out from the T port 25 via the sleeve 15 and the spool 16. Then, it is recovered in the recovery tank 6.

As described above with reference to FIGS. 1 and 6, the pressure oil is applied to the tail side of the first cylinder 4 and the second cylinder 5.
When the pressure oil from the rod side of the first cylinder 4 and the tail side of the second cylinder 5 is discharged while flowing into the rod side of the first cylinder 4, the piston rod 60 of the first cylinder 4 extends as shown in FIG. Then, the piston rod 61 of the second cylinder 5 retracts. As a result, as shown by the phantom line in FIG. 3, the front frame 43 turns left about the vertical axis 47, so that the front wheel 42 is switched to the left. Along with this, as shown by each phantom line (a) in FIGS. 3 and 4, the oscillating plate 50 rotates left about the vertical axis 47, so that the other end of the oscillating plate 50 moves forward. Is displaced to. Then, in accordance with this displacement amount, the connecting arm 58 is pulled forward, and the rotary shaft 35 rotates in one direction 62. This rotational force is transmitted to the drive shaft 28 via the second bevel gear 34 and the first bevel gear 33. As a result, the drive shaft 28 rotates, and the sleeve 15 rotates in one direction via the connecting pin 27. That is, when the handle 8 is turned to rotate the spool 16 in one direction, the sleeve 15 follows the spool 16 in the same direction by the same amount to eliminate the displacement of the spool 16, and thus the switching valve portion 9 The oil passage is fully closed. As a result, when the front wheels 42 are switched by the rotation angle of the handle 8, no more pressure oil is sent to the cylinders 4 and 5, and the front wheels 42 move to the handle 8
Accurately corresponds to the rotation angle of, and stops in the state of being switched to the left.

When the knob 59 is turned to rotate the handle 8 rightward to return it to the straight-ahead position, the spool 16 is switched to the CR positions as shown in FIG. 6, and the pressure oil from the hydraulic pump 1 is orbited. It is supplied to the tail side of the second cylinder 5 and the rod side of the first cylinder 4 through the switching valve portion 9 of the roll 3. At the same time, the pressure oil on the rod side of the second cylinder 5 and on the tail side of the first cylinder 4 flows into the recovery tank 6 through the spool 16.

That is, when the handle 59 is rotated clockwise by turning the knob 59 as described above, the spool 16 rotates in the other direction, so that the spool 16 is displaced relative to the sleeve 15. As a result, the oil passage is opened, and the pressure oil flowing from the P port 22 flows into the tail side of the second cylinder 5 and the rod side of the first cylinder 4 from the R port 23. At the same time, the pressure oil from the rod side of the second cylinder 5 and the tail side of the first cylinder 4 is discharged and returned to the L port 23,
It flows out from the T port 25 and is collected in the collection tank 6.

As described above, the pressure oil flows into the tail side of the second cylinder 5 and the rod side of the first cylinder 4, and the pressure oil of the rod side of the second cylinder 5 and the tail side of the first cylinder 4 as well. Is discharged, the piston rod 61 of the second cylinder 5 extends and the piston rod of the first cylinder 4
60 retreats. As a result, the front frame 43 rotates to the right, and the front wheels 42 are switched to the right. Along with this, the swing plate 50 rotates to the right, so the phantom line (b) in FIG.
As shown by, the other end of the oscillating plate 50 is displaced rearward. Then, in response to this displacement amount, the connecting arm 58 is pushed backward, and the rotary shaft 35 rotates in the other direction 63. This makes the second
The drive shaft 28 rotates via the bevel gear 34 and the first bevel gear 33, and the sleeve 15 rotates in the other direction. As a result, the sleeve 15 follows the spool 16 and rotates in the other direction by the same amount to eliminate displacement with the spool 16, and the oil passage of the switching valve portion 9 is fully closed. This allows
When the front wheel 42 is switched by the rotation angle of the handle 8, no more pressure oil is sent to the cylinders 4 and 5, and the front wheel 42 accurately corresponds to the rotation angle of the handle 8.
Stop with the switch to the right.

As described above, since the actual turning angle of the front wheel 42 is mechanically fed back by the link mechanism 64, the rotating shaft 35 and the gears 33, 34 to rotate the sleeve 15 in a predetermined direction, the switching of the orbit roll 3 is performed. Even if an oil leak occurs in the valve portion 9 or each of the cylinders 4 and 5, the pressure oil continues to be supplied to each of the cylinders 4 and 5 until the sleeve 15 closes the switching valve portion 9. The turning angle of corresponds exactly.

Therefore, even if the oil leaks as described above, the knob 59 is turned to rotate the handle 8 from the straight position to the left to switch the front wheel 42 to the left, and then the handle 8 is rotated to the right again. When returned to the straight position, the knob before turning the handle 8 and after returning the handle 8 to the original position
The position of 59 does not change.

In the above embodiment, the case where the handle 8 is rotated left from the linear position and then the handle 8 is rotated right to return to the linear position has been described, but after the handle 8 is rotated right from the linear position, The same applies when the handle 8 is rotated counterclockwise to return to the linear position.

In the above embodiment, by making the first and second bevel gears 33 and 34 of the orbit roll 3 compact, replacement with the conventional orbit roll can be easily performed.

[0033]

As described above, according to the present invention, a hydraulic type orbit roll using a rotary type switching valve is provided.
A first gear is provided at one end of a sleeve that is built in the switching valve and rotates in a predetermined direction to close the switching valve. A second gear that meshes with the first gear is provided, and a rotation shaft is provided at the second gear. By providing a link mechanism for connecting and rotating the rotary shaft according to the turning angle of the wheel, the actual turning angle of the wheel is mechanically fed back by the link mechanism, the rotating shaft, and the gear to prevent the sleeve. Since it can be rotated in a predetermined direction, even if oil leaks, the pressure oil continues to be supplied to the steering cylinder until the sleeve closes the switching valve, so the rotational operation amount of the steering wheel and the turning angle of the wheel correspond exactly. To do.

Therefore, for example, in a handle with a knob attached, even if oil leaks, after rotating the handle in one direction from the linear position by turning the knob,
When the knob is turned to rotate the handle in the opposite direction to return it to the straight position, the position of the knob does not change before the handle is rotated and after the handle is returned to the original position. This can prevent erroneous operation of the handle.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of an orbit roll of a power steering device according to an embodiment of the present invention.

FIG. 2 is a view on arrow AA in FIG.

FIG. 3 is a schematic plan view of an industrial vehicle having a power steering device.

FIG. 4 is a view on arrow BB in FIG.

5 is a view on arrow CC in FIG. 3. FIG.

FIG. 6 is a hydraulic circuit diagram of the power steering device.

FIG. 7 is a hydraulic circuit diagram of a power steering device in a conventional example.

FIG. 8 is a vertical sectional side view of an orbit roll of a power steering device in a conventional example.

[Explanation of symbols]

 3 Orbit Roll 4 1st Steering Cylinder 5 2nd Steering Cylinder 9 Switching Valve 15 Sleeve 33 1st Bevel Gear (1st Gear) 34 2nd Bevel Gear (2nd Gear) 35 Rotating Shaft 41 Wheel Loader (Industrial Vehicle) 42 Front Wheel 64 link mechanism

Claims (1)

[Claims] 1. A power steering device for an industrial vehicle, comprising a hydraulic orbit roll using a rotary switching valve, and a steering cylinder for switching a turning angle of wheels on a downstream side of the switching valve. And a second gear that meshes with the first gear is provided at one end of a sleeve that is built in the above-mentioned directional control valve and rotates in a predetermined direction to close the directional control valve. A power steering apparatus comprising a link mechanism for connecting a rotary shaft to the rotary shaft and rotating the rotary shaft according to a turning angle of a wheel.